Field of the Invention
The invention relates to a light source module, and particularly relates to a light source module having a tunable-focal length lens.
Description of Related Art
Most of lighting fixtures have their luminescent characteristics fixed before being delivered from manufacturers. However, under different climate conditions, optical behaviours of light beams are also different. Since climate conditions of different nations are different, various nations all have their own regulations to regulate the lighting fixtures.
For example, in a sunny day or in a low mist environment, concentration of moisture in the environment is relatively low, and light beam is easier to be propagated in an environmental medium in a straight-forward manner. In this case, the light beam with a higher color temperature is more suitable. On the other hand, in a rainy day or a misty environment, concentration of moisture in the environment is relatively high, and light beam is easier to be propagated in a scattering manner in such environment, so that propagation capability of beam energy is relatively poor, and in this case, the light beam with a lower color temperature is more suitable. However, the existing lighting fixtures have their luminescent characteristics fixed before being delivered from manufacturers, and the lighting fixtures are only adapted to a single environment, and have poor environmental adaptability. If the existing lighting fixtures are to be applied in different areas, lighting fixtures having different luminescent characteristics have to be correspondingly designed, which may greatly increase manufacturing cost. Moreover, even if the lighting fixtures with specific optical parameters are designed for a specific area, due to the changing climate, the lighting fixtures are not adapted to different environments. Therefore, to resolve the above problem has always been a target for related technicians of the field.